Changed to use sed for regex pattern matching
Changed to use sed for regex pattern matching

The code was using a mixture of shell patterns and
sed regular expression. Changed code to just used
sed regex. This will let me use more complex regex
that are needed for adding PARTUUID to uuids.

BUG=chromium:241572
TEST=./security_test_image
BRANCH=none

Change-Id: I2e8570051b31d580ae36cb82f05383a33236b88e
Reviewed-on: https://gerrit.chromium.org/gerrit/51503
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Commit-Queue: Paul Taysom <e180a809e49f87ec262dcf2e1499b58e80ddd4fa@chromium.org>
Tested-by: Paul Taysom <e180a809e49f87ec262dcf2e1499b58e80ddd4fa@chromium.org>

geekboxzone/mmallow_external_vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,geekboxzone/mmallow_external_vboot_reference,acorn-marvell/vboot_reference,coreboot/vboot,coreboot/vboot,acorn-marvell/vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,ccaapton/vboot_reference,ccaapton/vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,ccaapton/vboot_reference,ccaapton/vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference